Process for obtaining pure orthophosphoric acid from superphosphoric acid
AssigneeTexasgulf Inc.
InventorsJohn D. Jernigan, Brooks M. Whitehurst
Life of this patent
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Abstract
A process for obtaining pure orthophosphoric acid from superphosphoric acid is provided comprising: (a) hydrolyzing superphosphoric acid with water until a mixture of polyphosphoric acids and orthophosphoric acid is formed, wherein the total P.sub.2 O.sub.5 content of said mixture is from 65% to 70% and the poly P.sub.2 O.sub.5 content of said mixture is from 1% to 15% of the total P.sub.2 O.sub.5 ; (b) crystallizing said orthophosphoric acid from said mixture; (c) separating said orthophosphoric acid from said mixture; and (d) washing said orthophosphoric acid with an organic solvent having a low or limited solubility for orthophosphoric acid.
Claims18
A process for obtaining pure orthophosphoric acid from superphosphoric acid comprising:
- (a) hydrolyzing superphosphoric acid with water until a mixture of polyphosphoric acids and orthophosphoric acid is formed, wherein the total P.sub.2 O.sub.5 content of said mixture is from 65% to 70% and the poly P.sub.2 O.sub.5 content of said mixture is from 1% to 15% of the total P.sub.2 O.sub.5 ;
- (b) crystallizing said orthophosphoric acid from said mixture;
- (c) separating said orthophosphoric acid from said mixture;
- and
- (d) washing said orthophosphoric acid with an organic solvent selected from the group consisting of alcohols having six to nine carbon atoms and hydrocarbons having a low or limited solubility for orthophosphoric acid.
The process for the separation of pure orthophosphoric acid from superphosphoric acid which comprises:
- (a) heating superphosphoric acid with water until a mixture of polyphosphoric acids and orthophosphoric acid is formed wherein the total P.sub.2 O.sub.5 content of said mixture is from 65% to 70% and the poly P.sub.2 O.sub.5 content of said mixture is from 1 to 15% of the total P.sub.2 O.sub.5 ;
- (b) cooling said mixture to below about 75.degree. F to crystallize orthophosphoric acid therefrom;
- (c) centrifuging said mixture to separate substantially pure orthophosphoric acid;
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- (d) washing said orthophosphoric acid with an alcohol having from 6 to 9 carbon atoms.
A process for obtaining substantially pure orthophosphoric acid from superphosphoric acid which comprises:
- (a) heating a superphosphoric acid with water at a temperature of about 155.degree. to 185.degree. F until a mixture of orthophosphoric acid and low polyphosphoric acids is formed, containing 65 to 70% total P.sub.2 O.sub.5 and from 1% to 15% poly P.sub.2 O.sub.5 ;
- (b) cooling said mixture to a temperature below about 75.degree. F to crystallize orthophosphoric acid;
- (c) centrifuging said mixture to separate crystals of orthophosphoric acid from said mixture;
- and
- (d) washing said orthophosphoric acid crystals with an alcohol having from six to nine carbon atoms.
A process for obtaining substantially pure orthophosphoric acid from a superphosphoric acid which comprises:
- (a) heating a superphosphoric acid containing from about 69% to 71% P.sub.2 O.sub.5 with water at a temperature from about 155.degree. to 185.degree. C for from about 1/2 to 1 hour to form a mixture of orthophosphoric acid and low polyphosphoric acids containing 65-70% total P.sub.2 O.sub.5 and from 1% to 15% poly P.sub.2 O.sub.5 ;
- (b) cooling said mixture to a temperature below about 75.degree. F;
- (c) adding seed crystals of anhydrous orthophosphoric acid to said mixture to initiate crystallization of orthophosphoric acid;
- (d) maintaining said mixture at a temperature below about 75.degree. F for from about 1.5 to 10 hours to complete the crystallization of said orthophosphoric acid;
- (e) centrifuging said mixture to separate crystals of orthophosphoric acid from said mixture;
- and
- (f) washing said orthophosphoric acid crystals with 1-heptanol.
Dependencies are inferred from the claim text.